This is a continuing study of the pathophysiology of the thyroid gland. Current research includes observations on intemediary metabolism of the thyroid in patients with simple goiter and those with inherited thyroid disorders, fetal-maternal relationships in terms of thyroid function as influenced by protein and iodine deprevention, thyroid effects of chronic SCN minus and CN minus administration, the auditory defect in iodine deficiency, and thyroid plasma membrane preparation and properties. The aim of these studies is to understand better the origin and nature of human thyroid disease.